/**
 * Created by Administrator on 2016/4/2.
 */
import java.util.Scanner;
public class Average{
    public static void main(String[] args){
        Scanner console=new Scanner(System.in);
        double sum=0;
        int count=0;
        while(true){
            int number=console.nextInt();
            if(number==0){
                break;
            }
            sum+=number;
            count++;
        }
        System.out.printf("平均 %.2f%n",sum/count);
    }
}